Endoparasiticidal gel composition

Abstract

A homogenous, clear, veterinary gel composition which has a broad spectrum of efficacy against endoparasites over a prolonged period of time and which allows for higher concentrations of a mixture of parasiticidal agents in a single application. This composition is useful for treating and controlling endoparasiticidal infection and infestation in a homeothermic animal.

1. A method for the preparation of an endoparasiticidal gel composition comprising about 1.0% to 3.5% wt/wt of moxidectin; about 10.0% to 15.0% wt/wt of praziquantel; about 4.0% to 24.0% wt/wt of benzyl alcohol; about 1.0% to 34.0% wt/wt of ethanol; about 2.0% to 15.0% wt/wt of colloidal silicon dioxide; about 1.0% to 20.0% wt/wt of a surfactant; and about 35.0% to 61.0% wt/wt of an oil, which comprises the following steps:
 a). dissolving a thickener in a mixture of benzyl alcohol and ethanol to form a solution A; 
 b). mixing an oil with praziquantel to form a suspension B: 
 c). admixing solution A with suspension B at temperatures ≦50° C. until a solution C which is homogeneous at room temperature is obtained; 
 d). admixing surfactant and optionally butylated hydroxytoluene with solution C to form solution D; and, 
 e). sequentially admixing moxidectin and colloidal silicon dioxide to solution D to form gel E, wherein gel E is a non-aqueous composition. 
 
     
     
       2. The method of  claim 1  further comprising the step:
 f). mixing get E under a vacuum to form a clear yellow endoparasiticidal gel composition that is essentially free of air. 
 
     
     
       3. The method according to  claim 1  wherein the oil is propylene glycol dicaprylate/dicaprate and the thickener is ethyl cellulose. 
     
     
       4. The method according to  claim 3  wherein the surfactant comprises a polyoxyethylene sorbitan ester. 
     
     
       5. The method according to  claim 4  wherein said polyoxyethylene sorbitan ester is polysorbate 80.